单边凹槽电极结构MSM型蓝光探测器的研究

MSM Blue-Light Photodetector with Unilateral Recessed Electrode Structure

摘要:

为提升InGaN基可见光探测器性能,制作并测试了基于GaN/InGaN MQWs外延材料的单边凹槽叉指电极MSM结构蓝光光电二极管。凹槽电极器件的I-V特性测试结果显示,相较于传统平面电极器件,随着偏压增加,器件暗电流越小且越趋于平缓,而光电流越大；光谱响应率测试显示,器件截止带边都位于490nm附近,凹槽电极器件带边处拒绝比高于平面电极器件1个量级。当偏压为5V时,凹槽电极器件响应率为0.0346A/W@480nm,对应外量子效率为8.94%,高于平面电极器件。器件性能提升的原因是单边凹槽电极结构有效改善了内建电场的分布,从而抑制了表面传导漏电流,使得器件暗电流更小且更有利于电极收集光生载流子,提升了响应率。

Abstract:

To improve the performance of InGaN-based visible light detectors, a unilateral recessed interdigital electrode MSM-type blue light photodiode based on a GaN/InGaN MQWs epitaxial material is fabricated and measured. The I-V characteristic measurement results of the device show that, compared with traditional planar electrode devices, recessed electrode devices have smaller and flatter dark currents and larger photocurrents with increasing bias. Spectral response measurements show that the cutoff band edge of the device is located near 490nm, and the rejection ratio at the band edge of the recessed electrode device is one order of magnitude higher than that of the planar electrode device. At a bias voltage of 5V, the responsivity of the recessed electrode device is 0.0346A/W@480nm, corresponding to an external quantum efficiency of 8.94%, that is higher than that of the planar electrode device. The improvement in device performance is attributed to the effective suppression of the surface conduction leakage current and the improved distribution of the built-in electric field achieved by the unilateral recessed electrode structure. This results in a reduced dark current in the device and enhances the collection of photogenerated carriers by the electrodes, thereby increasing the responsivity.